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Collection: Directories and Documents > Pamphlets

Minerology Handbook by Eckert Mineral Research Prospector Supplies (PH 2-2) (28 pages)

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V. PHYSICAL PROPERTIES A systematic determination is the best procedure in studying a new specimen. First, we must learn all we can from observation and trom handling the mineral. The following is a lst of characteristics to observe, or as the chemist calls them, the PHYSICAL PROPERTIES. A, PROPERTIES DEPENDING UPON COHESION—Cohesion refers to the form of attraction by which the particles of a body are united throughout the mass. Under this heading are the following subdivisions: 1, Cleavage—Some minerals break more persistently in certain directions than in others. Thus, Galena, because it breaks readily into little cubes, is said to have cubic cleavage. The following is a cleavage list of some of the common minerals: Cubic Cleavage.................-. Galena, Fluorite, Pyrite Octahedral Quartz Dodecahedral Zine Blende Rhombohedral Dolomite 2, Hardness—By hardness the mineralogist means the capacity which & mineral has for scratching another substance, or the resistasce which it offers to another substance tending to scratch it. Hardness is expressed in terms of the following scale. THE SCALE OF HARDNESS 1, Tale 6. Orthoclase (Feldspar) 2. Gypsum 7. Quartz 3. Calcite 8. Topaz 4, Fluorite 9. Corundum, (Sapphire) 5. Apatite 10, Diamond Every mineral in this list will scratch the one hefore it and be scratched by the one following it. When we say a mineral has a hardness of 6, (denoted by the Symbol H6), we know that it is as hard as orthoclase, that it will scratch numbers 1, 2, 3, 4, 5, and that it will be scratched by numbers 7, 8, 9, 10. When a mineral is said to have a hardness of 4.5 we mean it is a little harder than Fluorite and a little softer than Apatite. When two minerals scratch each other they have equal hardness. B. PROPERTIES DEPENDING UPON LIGHT 1, Luster—By luster we mean the appearance of the surface of a mineral as affected by, or dependent upon peculiarities of its reflecting qualities. The principa) kinds of luster are: A, Metallic—Having the metallic appearance of steel, tin, zinc, or other metals. Minerals having this type of luster are Stibnite, Galena, Pyrite, Hematite. B, Adamantine—A brilliant, sparkling luster. Examples: Diamond, Corundum, Cassiterite, etc. —8—